High-voltage terminal



Patented Sept. 28, 1948 UNITED STATES PATENT OFFICE HIGI-LVOLTAGETERMINAL Application April 13, 1945, Serial No. 662,036

4 Claims.

This application is a continuation-in-part of my copending applicationSerial No. 466,901, filed November 25, 1942, for Electrical capacitor,now Patent No. 2,398,417.

This invention relates to high voltage terminals for enclosed electricalapparatus and more particularly to such terminals for electricalapparatus, for example electrical condensers, for operation at very highfrequencies as is the case with apparatus used in radio transmitters.

In electrical apparatus, such as condensers, enclosed in a casing withor without a filling of oil or other insulating fluid, the constructionof satisfactory high voltage terminals for carrying heavy currents ofthe order of 50 amperes and upwards at high frequencies becomesdifiicult as terminals and conductors of normal construction become hotwith the result that the losses are seriously increased and may in somecases be come greater than those of the apparatus itself.

' This difiiculty can be overcome by dividing the current between two ormore conductors, as has been proposed in the past, and the main objectof the present invention is to provide an improved terminal ccnstructionfor such a multiple conductor arrangement.

The invention as to its further objects and novel aspects will becomemore apparent from the following detailed description taken in referenceto the accompanying drawings forming part of this specification, andwherein:

Figure 1 is a cross-section through a terminal structure constructed inaccordance with the principles of the invention.

Figure 2 shows amodification of the terminal structure according to theinvention.

Like reference characters identify like parts in both views of thedrawings.

Referring more particularly to Figure 1, it has been assumed that theterminal shown constitutes the high voltage terminal of a condenser (notshown in the drawing) housed in a metal casing IE], only part of whichis shown, the casing constituting the other terminal of the condenser.The casing 10, which may be either cylindrical or square, is closed by acover ll preferably of insulating material, such as ground mica and abinder compressed into solid shape and known under the registeredtrade-mark "Mycalex or the like, fixed to a flange of the casing bymeans of bolts l2, a gasket l3 being provided to maintain the jointliquid-tight. The cover H has a central circular opening M, the edge l5of which is of reduced thickess so as to provide on each side of thecover seatings for annular gaskets I6 and I1 consisting of cork or otherseating material impervious to any liquid used for filling the casing,and having a channelshaped cross-section. Seated on the gaskets It andll are the inner ends of a pair of insulating tubes l8 and 29 preferablyconsisting of heatrcsisting glass such as the material sold under theregistered trade-mark Pyrex or the like. The outer ends of the tubes Itand 20, respectively, fit into further gaskets 2| and 22 in annulardepressions in a pair of discs 23 and 24 of insulating material such,for example, as a phenolic condensation product known under theregistered trade-mark Bakelite.

The discs 23 and 24 are pressed against the tubes l8 and 2t) and thegaskets on the cover H by means of conducting rods 25 and 26, extendingthrough the tubes and having their ends passing through the discs 23-and2d. The lower ends of the rods 25 and iii are secured on both sides ofthe disc '24 by means of nuts 21, 28 and 3B, 3!, respectively, and thenthe whole terminal structure is clamped in a rigid and liquidtightmanner by nuts 32 and 33 on the upper ends of the rods and on the outersurface of the disc '23.

Suitable washers or gaskets 34 and 35 (or a single washer) of cork orthe like are interposed between the nuts 21, 28 and the disc 2A to makethe joint liquid-tight. Terminal strips or leads 3% and 31 from thecondenser or other electrical device (not shown) in the casing areclamped below the nuts 21, 28 so as to be electrically connected to theconducting rods 25 and 2.6, which are preferably made of copper.

The projecting upper ends of the rods 25 and 26 may be joined by acommon connecting element such as a metal washer 38 clamped between thenuts 32, 33 and the disc 23, and additional terminal nuts 43, M may beprovided for connections from the condenser to the other apparatus in anelectrical system. While only two conducting rods 25 and 26 appear inthe figure, actually the construction shown preferably has four,although any desired number from two upwards may be provided in orderthat there may be two or more separate paths for the current flowthrough the terminal.

This improved insulated terminal structure, besides enabling simpleparts of relatively inexpensive materials to be used, has the furtheradvantage that no continuous path exists through the dielectric betweenthe high potential terminal and the casing. Consequently, the electricstrain in the dielectric material is greatly reduced. This makes itpossible to use a cheaper material or to increase substantially theoperating voltage for which a. terminal of given size can be used.

Thus, electric flux will pass from the casing 18 through the cover H tothe edge of the opening M and from there through intervening air spaceto the high potential conductors 25 and 26. Only a small amount of fluxwill pass through the considerably longer path offered by the tubes I8,20, discs 23, 24, and the intervening air gaps. Accordingly, therefore,the dielectric material of the cover II will be greatly relieved ofelectrical stress, so that the operating safety is substantiallyincreased or a higher operating voltage can be used.

In addition to the improved dielectric properties referred to above, thedivision of the current between two or more parallel conductors preventsor reduces over-heating and thus avoids the disadvantages referred toabove.

It will be appreciated that the above description is by way of exampleonly and that structural details may be varied within the scope of theinvention. Thus, instead of using open-ended tubes, these members may beformed with one end closed, that is, may be cup-shaped as shown at 44and 45 in Figure 2, and assembled with their open ends abutting againstthe edge l of disc or cover I i the conductors passing through suitablyformed holes in the closed ends. Furthermore, the conductors themselvesmay consist of wires or strips (instead of rods with screwthreaded ends)and may be secured in position after assembly and the application ofsufficient tension to insure that the joints are liquid-tight, bywelding or soldering the lugs thereon or in any other convenient manner.

While I have shown and described a desirable embodiment of theinvention, it is understood that this disclosure is for the purpose ofillustration and that various changes in shape, proportion andarrangement of parts, as well as the substitution of equivalent elementsand materials for those herein shown and described, may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims. The specification and drawing are accordingly to beregarded in an illustrative rather than a limiting sense.

I claim:

1. A terminal structure for a high frequency, high voltage apparatusenclosed in a metallic casing having an insulating wall provided with anopening, comprising a pair of cup-shaped insulating members each havinga bottom portion and a cylindrical portion separate therefrom andengaging a groove of said bottom portion, said members being arranged oneach side of said wall with the open ends of said cylindrical portionsabutting against the opposite edge zones of said wall around saidopening, a plurality of conductors passing through said opening and saidbottom portions, said conductors being spaced from each other and fromthe edge of said opening, and means for mechanically securing saidconductors to said bottom portions to hold the complete assemblytogether.

2. A terminal structure for a high frequency, high voltage apparatusenclosed in a metallic casing having an insulating wall provided with anopening, comprising an insulating wall member provided with an opening apair of cup-shaped insulating members having cylindrical and bottomportions and arranged on each side of said wall with the ends of saidcylindrical portions abutting against opposite seatings of reducedthickness of saidv wall around said opening, a plurality of conductorspassing through said opening and the bottom portions of said members,said conductors being spaced from each 'other and from the edge of saidopening, and

means for securing said conductors to said bottom portions to hold thecomplete assembly together.

3. A terminal structure for a high frequency, high voltage apparatusenclosed in a metallic casing having an insulating wall provided with anopening, comprising an insulating wall member provided with an opening,a pair of cupshaped insulating members having cylindrical and bottomportions and arranged on each side of said wall with the inner ends ofsaid cylindrical portions abutting against opposite seatings of reducedthickness of said wall around said opening, sealing gaskets interposedbetween said members and said seatings, a plurality of conductorspassing through said opening and the bottom portions of said members,said conductors being spaced from each other and from the edge of saidopening, and means for securing said conductors to said bottom portionsto hold the complete assembly together.

4. A terminal structure for a high frequency, high voltage apparatusenclosed in a metallic casing having an insulating wall provided with anopening, comprising a pair of cup-shaped insulating members each havinga bottom portion and a cylindrical portion separate therefrom andengaging a groove of said bottom portion, said members being arranged oneach side of said wall with the open ends of the cylindrical portionsabutting against the opposite edge zones of said wall around saidopening, a plurality of conductors passing through said opening and thebottom portions of said members, said conductors being spaced from eachother and from the edge of said opening, means for securing saidconductors to said bottom portions to hold the complete assemblytogether, and sealing gaskets interposed between the cylindrical andbottom portions of said members and between said members and said wall.

WILLIAM DUBILIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 608,906 Poche Aug. 9, 18981,089,549 Halbleib Mar. 10, 1914 1,160,702 Faccioli Nov. 16, 19151,932,456 Gaston Oct. 31, 1933 FOREIGN PATENTS Number Country Date 7233,880 Great Britain May 21, 1925 77,584 Sweden Feb. 17, 1932

